Float bath for manufacturing glass; float glass forming method utilizing the same and method for installing barriers to the float bath

ABSTRACT

A float bath for manufacturing glass includes a slot formed in a bottom block of the float bath in which a molten metal is to be filled, a barrier member capable of being inserted into the slot, a receiving portion formed in at least one side block that connects with the bottom block so as to communicate with the slot, and a placing member placed in the receiving portion to be connected to one end of the barrier member.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119(a) to Korean PatentApplication No. 10-2010-0036528 filed in Republic of Korea on Apr. 20,2010, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a float bath for manufacturing glass, afloat glass forming method using the float bath, and a method forinstalling barriers to the float bath. More particularly, the presentinvention relates to a float bath for manufacturing glass, which has animproved barrier installation structure for controlling the flow of amolten metal received in the float bath, a float glass forming methodusing the float bath, and a method for installing barriers to the floatbath.

2. Description of the Related Art

Generally, an apparatus for manufacturing a float glass (also known assheet glass, flat glass, or plate glass) using a float glass process isused to manufacture a float glass having a predetermined size (width,thickness, or the like) by continuously supplying molten glass onto aflowing molten metal such as molten tin or tin alloy stored in a floatbath, floating the molten glass on the molten metal to form a moltenglass ribbon into a band shape with a constant thickness, and pulling upthe glass ribbon toward an annealing lehr near an exit of the floatbath.

Here, the molten metal includes, for example, tin or tin alloy, and hasa greater specific gravity than the molten glass. The molten metal isreceived in a float chamber where a reducing atmosphere of hydrogen (H₂)and/or nitrogen (N₂) gas is introduced. The float bath in the floatchamber is configured to contain the molten metal therein. The floatbath has a horizontally extending structure and includes a high heatresistant material (for example, bottom blocks) therein. The moltenglass forms a molten glass ribbon while moving from an upstream end ofthe float bath to a downstream end. The molten glass ribbon is lifted upat a location (hereinafter, referred to as a take-off point) set on thedownstream end of the float bath to stay away from the molten metal, anddelivered to an annealing lehr of the next process. Meanwhile, an inletand an outlet of the float chamber should have certain temperaturegradients. The molten metal contacting the molten glass and the uppersite in the float chamber should also have temperature gradients.

However, since tin frequently used as the molten metal rapidlypropagates heat and is in liquid state, the temperature gradient in thefloat bath may be easily broken due to heat convection which equalizesthe temperature. Thus, the float bath should have a sufficient length.Similarly, so that the atmosphere of the upper portion of the moltenmetal has a predetermined equalized temperature difference byconvection, the float bath needs a sufficiently long structure. Also,shaping members such as so-called ‘top-roll’ are disposed at apredetermined region of the float bath to enlarge the width of the glassribbon and thus adjust the thickness of the float glass. Thus, theregion where top-rolls are disposed is heated by heating members. Due tothis condition, it is also necessary to increase the length of the floatbath.

FIG. 1 is a side sectional view showing a conventional float bath, andFIG. 2 is a partially sectioned perspective view showing theconventional float bath of FIG. 1.

Referring to FIGS. 1 and 2, a conventional float bath 1 has a barriermember 3 installed in a width direction of a bottom block 2. The barriermember 3 functions to decrease or limit mixing of molten metals Mbetween a high temperature region and a low temperature region in thefloat bath 1 to maintain a desired temperature difference (gradient)between two regions. In other words, the barrier member 3 plays a roleof keeping the molten metal M in a high temperature forming region atthe upstream of the float bath 1. The barrier member 3 is generally madeof carbon material, or the like. Also, the barrier member 3 is insertedinto a dovetail slot 4 formed in the bottom block 2. An installationgroove 6 is provided in the bottom block 2 adjacent to a side block 5 ofthe float bath 1 so that the barrier member 3 is inserted therein.

However, since the upper portion of the installation groove 6 is openedwhile the float bath 1 forms a float glass G, the molten metal 6 iscollected in the installation groove 6. In addition, the molten metal Mmay float in a region above the installation groove 6. As a result, thebarrier member 3 of the conventional float bath 1 is not able to blockthe flow of the molten metal M in at least one end of the float bath 1in a width direction. Also, the barrier member 3 is limited incontrolling the flow of the molten metal M since the molten metal Mcollected in the installation groove 6 may flow in whirls.

Meanwhile, there are some conventional cases where a barrier isinstalled over the entire length of a bottom block in a width direction.However, for this purpose, a side block should be installed afterbarriers are installed over the entire length of the bottom block. Inthis case, when it is needed to repair or exchange the barrier, the sideblock should be dismantled from the bottom block, which is verydifficult and not economic.

SUMMARY OF THE INVENTION

The present invention is conceived to solve the problems of the priorart, and therefore the present invention is directed to providing afloat bath for manufacturing glass, which allows a barrier member to bestably and easily installed over the entire length of the float bath ina width direction and also ensures easy maintenance and exchange of thebarrier member without dismantling a side block from a bottom block. Thepresent invention is also directed to a float glass forming method usingthe float bath, and a method for installing barriers to the float bath.

In one aspect, the present invention provides a float bath formanufacturing glass, which includes a slot formed in a bottom block ofthe float bath in which a molten metal is to be filled; a barrier membercapable of being inserted into the slot; a receiving portion formed inat least one side block that connects with the bottom block so as tocommunicate with the slot; and a placing member placed in the receivingportion to be connected to one end of the barrier member.

Preferably, the placing member includes a barrier part contacting atleast one end of the barrier member to give a barrier function over theentire length of the float bath in a width direction thereof; and a sidepart protruding perpendicular to the barrier part to form substantiallythe same plane as the side block.

Preferably, the float bath further includes a fastener for fixing theplacing member to the receiving portion.

Preferably, the fastener includes a fixing protrusion capable of beinginserted into a fastener groove formed in the placing member; and afastener body extending from the fixing protrusion to be installed tothe side block.

Preferably, the slot has a dovetail shape, and the barrier has an insertportion with a dovetail shape, which is capable of being inserted intothe dovetail-shaped slot.

Preferably, the barrier member has a plurality of barriers successivelycontacting each other and having a predetermined length.

Preferably, the barrier member is made of the same material as thebottom block.

Preferably, the barrier member includes a firebrick.

In another aspect of the present invention, there is also provided amethod for installing barriers to a float bath that includes a bottomblock with a slot in a width direction thereof and a side block with areceiving portion communicating with the slot, the method including (a)inserting a plurality of barriers into the slot successively through thereceiving portion; (b) positioning a placing member to the receivingportion so that the placing member is located in contact with anoutermost barrier closest to the side block; and (c) fixing the placingmember.

In still another aspect of the present invention, there is also provideda method for forming a float glass, which includes successivelysupplying a glass in a molten state onto the molten metal from one endof the float bath; forming the glass on the molten metal into a glassribbon; and successively pulling the glass ribbon from the other end ofthe float bath.

The float bath for manufacturing glass, the float glass forming methodusing the float bath, and the method for installing barriers to thefloat bath according to the present invention have the followingeffects.

First, since the barrier member may be conveniently installed over theentire bottom surface of the float bath, the temperature gradientdemanded by the float bath may be more stably maintained.

Second, the barrier may be easily separated through a receiving portionformed at the side block without dismantling the side block from thebottom block.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and aspects of the present invention will become apparentfrom the following description of embodiments with reference to theaccompanying drawing in which:

FIG. 1 is a side sectional view showing a conventional float bath;

FIG. 2 is a partially sectioned perspective view showing theconventional float bath of FIG. 1;

FIG. 3 is a side sectional view showing a float bath according to apreferred embodiment of the present invention;

FIG. 4 is a partially sectioned perspective view showing the float bathof FIG. 3;

FIG. 5 is a partially sectioned perspective view schematicallyillustrating a process of inserting barriers to a bottom block accordingto a preferred embodiment of the present invention; and

FIG. 6 is a plane view showing a coupling state of the float bath ofFIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

It should be understood that the terms used in the specification and theappended claims should not be construed as limited to general anddictionary meanings, but interpreted based on the meanings and conceptscorresponding to technical aspects of the present invention on the basisof the principle that the inventor is allowed to define termsappropriately for the best explanation. Therefore, the descriptionproposed herein is just a preferable example for the purpose ofillustrations only, not intended to limit the scope of the invention, soit should be understood that other equivalents and modifications couldbe made thereto without departing from the spirit and scope of theinvention.

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 3 is a side sectional view showing a float bath according to apreferred embodiment of the present invention, FIG. 4 is a partiallysectioned perspective view showing the float bath of FIG. 3, FIG. 5 is apartially sectioned perspective view schematically illustrating aprocess of inserting barriers to a bottom block according to a preferredembodiment of the present invention, and FIG. 6 is a plane view showinga coupling state of the float bath of FIG. 3.

Referring to FIGS. 3 to 6, a float bath 100 for manufacturing glassaccording to this embodiment includes a slot 112, formed in a bottomblock 110 of the float bath 100, barrier members 120 that may beinserted into the slot 112, a receiving portion 132 formed in a sideblock 130 that contacts the bottom block 110 so that the receivingportion 132 is communicated with the slot 112, and a placing member 140placed on the receiving portion 132 and connectable to one end of atleast one of the barrier members 120.

The float bath 100 of this embodiment is used for manufacturing glass bya so-called floating process, and the upper portion of the float bath100 is substantially sealed by a roof (not shown) having electricresistance heating elements (not shown).

Molten metal M such as molten tin or molten tin alloy is stored in thefloat bath 100. Molten glass G flows into the float bath 100 with itsflow rate being controlled by a gate (not shown) located at the upstreamof the float bath 100. While the molten glass G moves from the upstreamof the float bath 100 to the downstream, the molten metal M flows by themolten glass G. In this process, the molten metal M flows from upstreamto downstream of the float bath 100 that is kept at relatively hightemperature by the temperature gradient in the float bath 100, and alsothe molten metal M flows from the center of the float bath 100 to bothsides. While moving from the upstream to the downstream, the moltenglass G is formed into a thin ribbon shape with desired thickness andwidth and is pulled by lift-out rollers (not shown) installed at theoutlet of a float chamber to go away from a bath surface of the moltenmetal M at a take-off point. Also, after passing over the lift-outroller, the float glass G moves toward an annealing lehr (not shown) ofthe next process.

The inner circumference of the float chamber is composed of a gasmixture of nitrogen and hydrogen, and the gas mixture is kept with apressure slightly higher than an ambient pressure. The molten metal Mand the ribbon-shaped molten glass G are kept at about 600 to 1,300° C.by means of electric resistance heating elements. The molten glass G isnon-alkali glass, soda-lime glass, or the like. Flow generatingprinciple and structure of the molten metal M in the float bath 100 aswell as introduction, ribbon-shaping, movement and discharge of themolten glass G are already well known in the art as a floating process,and they are not described in detail here.

The bottom block 110 of the float bath 100 has a structure in which aplurality of bricks B (see FIG. 5) containing refractory materials suchas firebricks is coupled by lining. The bottom block 110 is surroundedand protected by a steel casing (not shown). A gap between bricks B ofthe bottom block 110 of the float bath 100 is preferably determined inconsideration of the height of the bricks themselves. Also, individualbricks B need corrosion resistance for the molten metal M, alkaliresistance for K₂O or Na₂O included in the glass G, and anti-spallingproperty for coping with temperature change accompanied by exchange orchange of a glass product. Also, side blocks 130 contacting the bottomblock 110 are installed at both sides of the float bath 100.

The slot 112 formed in the bottom block 110 is for example provided neara shoulder zone that is narrowed from a high temperature wide zone (notshown) at the upstream of the float bath 100 to a low temperature narrowzone (not shown) at the downstream. The slot 112 is preferably formed tohave a dovetail shape. The slot 112 is formed over the entire length ofthe float bath 100 in a width direction.

Meanwhile, as shown in FIGS. 4 and 5, the slot 112 has a first portion114 having a dovetail shape so that the barrier member 120 is insertedand then fixed therein, and a second portion 116 for inserting thebarrier member 120 from at least one side of the bottom block 110 towardthe center. The first portion 114 of the slot 112 has a dovetail shapeas mentioned above. However, the second portion 116 has a width greaterthan the width of an insert portion 122 of each barrier 121 and a lengthgreater than at least the length of each barrier, as described above, soas to provide a space through which the barrier member 120 may beinserted. Also, the second portion 116 of the slot 112 is preferablyformed at both sides of the float bath 100. In this case, the barriermember 120 may be inserted from both sides of the float bath 100 to thecenter, which facilitates the installing work of the barrier member 120.In addition, it becomes easier to set the number of barriers 121appropriately in consideration of the length of the float bath 100.

The barrier member 120 is used to decrease and/or limit mixing themolten metals M between the wide zone and the narrow zone of the floatbath 100, and the barrier member 120 plays a role of keeping the moltenmetal M at the high temperature upstream in a forming zone. The barriermember 120 of this embodiment is not moved but fixed to the bottom block110. The barrier member 120 is located very close to the lower surfaceof the molten glass G while being immersed in the molten metal M storedon the bottom block 110 but is fixed at a location not contacting thelower surface of the molten glass G. Thus, the size (particularly,height) of the barrier member 120 is obvious to those of ordinary skillin the art and is thus not described in detail here.

The barrier member 120 includes a plurality of barriers 121 successivelycontacting each other and having a predetermined length. Each barrier121 is made with the same material of the bottom block, for example afirebrick. As mentioned above, the barrier 121 includes the insertportion 122 having a dovetail shape that may be inserted into the slot112, and a barrier body 124 protruding from the insert portion 122. Theconventional carbon material of the barrier member 120 is replaced withrefractory material in the present invention so as to prevent any smalldefects that may occur when the barrier member 120 is oxidized due tooxygen or the like present in the float bath 100.

The side block 130 includes a receiving portion 132 at an areacontacting the bottom block 110 of the float bath 100. The receivingportion 132 is formed as a depressed region in the inner side of theside block 130 to have substantially the same width as the secondportion 116 of the slot 112.

The placing member 140 is inserted into the receiving portion 132 of theside block 130 and the second portion 116 of the slit 112 to extend atleast one end of the barrier member 120 till the side block 130, andthus the placing member 140 plays a role of extending the length of thebarrier member 120 over the entire width of the float bath 100. In otherwords, the placing member 140 contacts at least one end of the barriermember 120 to give a barrier function against the molten metal M overthe entire width of the float bath 100 at both sides of the float bath100. For this purpose, the placing member 140 includes a barrier part142 located in the second portion 116 of the slot 112, and a side part144 protruding perpendicular to the barrier part 142 and located at thereceiving portion 132 to form substantially the same plane as the sideblock 130. Thus, the placing member 140 has an “L”-shaped sectionalshape. Also, a horizontal portion of the placing member 140 is thebarrier part 142, and a vertical portion thereof is the side part 144.The placing member 140 is made of the same material as the side block130.

In an alternative embodiment, the slot 112 formed in the bottom block110 of the float bath 100 may have only the first portion 114 while nothaving the second portion, and the receiving portion 132 of the sideblock 130 in the former embodiment may function as the second portion.In this case, it would be understood by those of ordinary skill in theart that the receiving portion 132 may be formed to have a sufficientlength in a width direction of the side block 130 so that individualbarriers 121 may be inserted therein.

The float bath 100 of this embodiment further includes a fastener 150for fixing the placing member 140 located in the receiving portion 132.The fastener 150 may have a “T” shape, for example, and this T-shapedfastener 150 includes a fixing protrusion 152 that may be inserted intoa fastener groove 145 formed in the upper surface of the side part 144of the placing member 140, and a fastener body 154 extending from thefixing protrusion to be installed to the side block 130. It is obviousto those of ordinary skill in the art that the fastener 150 may useother kinds of coupling members such as a hook and a bolt, in additionto the T shape.

In an alternative embodiment, it is obvious to those of ordinary skillin the art that the barrier member 120 may be applied to various kindsof barrier systems that are fixed in a length direction of the floatbath 100.

The present invention has been described in detail. However, it shouldbe understood that the detailed description and specific examples, whileindicating preferred embodiments of the invention, are given by way ofillustration only, since various changes and modifications within thespirit and scope of the invention will become apparent to those skilledin the art from this detailed description.

1-8. (canceled)
 9. A method for installing barriers to a float bath thatincludes a bottom block with a slot in a width direction thereof and aside block with a receiving portion communicating with the slot, themethod comprising: (a) inserting a plurality of barriers into the slotsuccessively through the receiving portion; (b) positioning a placingmember to the receiving portion so that the placing member is located incontact with an outermost barrier closest to the side block; and (c)fixing the placing member.
 10. A float bath, which is installed inaccordance with the method of claim
 9. 11-12. (canceled)